Congrats if this is your first trip into the class three world. Unfortunately there is no turning back from here . If this is your first purchase, I sure you have found that the paperwork is really not that bad and you are already looking for an entry SMG. If this isnt your first one disregard above and read below.
As for the outback, I really like it. A couple of people who's opinions I really respect say that there are some srew ons that are a little quieter but not by much. I think with the right ammo (subsonic might be necessary depending on the bbl length of your pist) you will be very pleased. If you really want it quieter, you can always put about a teasponfull of water in the back end (per Dr daters instructions) to really push the volume down. Some guys even use hair gel but I have not tried that. Also Gem-Tech customer service is incredible!!:t